Being able to boost documents is a powerful capability, making it easy for you to emphasize certain information. Boosting is done in a source via an XSL parser, in which it is important to only add boost-related information while preserving all other attributes and XML elements.
Boosting by itself is not very interesting. Boosting must be combined with spotlighting, the ability to specially display and format boosted elements, in order to be truly useful. Together, boosting and spotlighting can help you create user-oriented applications that place the information that your users need in convenient and prominent locations in the results of their queries.